A rotary solenoid includes a stator and a rotor. The stator includes a rectangular iron core with two stator poles extending from two opposing inner surfaces thereof and two coils wound about the two stator poles. The rotor is located between the two stator poles and includes two rotor poles extending in opposing direction. During operation, when the two coils are activated, the two stator poles generate a magnetic field that interacts with and attracts the two rotor poles, thereby driving the rotor to rotate. However, as there are two coils wound around the two stator poles, saturation flux density in the iron core and the stator poles is high. Flux path of this rotary solenoid is rectangular and is relatively long. Further, the interaction area between the stator pole and the rotor pole is small because there are only two rotor poles. All these features would limit the output torque of the solenoid.
The present invention aims to provide a new solenoid having high output torque.